CHAP, in.] ELIMINATION OF WASTE PRODUCTS. 677 



398. The connective-tissue which binds together the tubules 

 and blood vessels is exceedingly scanty. Some small amount 

 enters with the blood vessels, and is continued on along their 

 larger branches, but in the cortex the " stroma " consists of hardly 

 more than the basement membranes of the tubules, with a few 

 connective-tissue corpuscles imbedded in a scanty homogeneous 

 not fibrillated matrix lying between them; around the capsules 

 this stroma is rather more abundant than elsewhere, and here 

 is sometimes fibrillated. In the pyramids, especially at their 

 lower parts, a larger amount of a similar homogeneous matrix, 

 containing connective-tissue corpuscles, is found between the 

 tubules; and since here the basement membrane of the tubule 

 is fused with this stroma, the tubule appears as a tubular 

 cavity hollowed out of the matrix or stroma and lined with 

 epithelium. 



The whole kidney is surrounded by a capsule, consisting of 

 ordinary connective-tissue and continuous at the hilus with the 

 connective-tissue forming the outer walls of the pelvis and ureter. 

 This capsule may after death be peeled off, and slender processes of 

 connective-tissue with some blood vessels passing from the capsule 

 into the cortex are then disclosed. 



In the scanty stroma are numerous lymph-spaces, the lymph 

 from these being collected into lymphatic vessels which in part 

 leave the kidney by the hilus together with the blood vessels, and 

 in part run in the capsule and leave the kidney on its convex 

 surface. The capsule is described as separable into two layers, and 

 the lymphatic vessels run chiefly between these layers. 



399. As the renal artery passes to the kidney it is invested 

 by a number of (twenty or less, in the dog a dozen or more) nerves, 

 arranged in a plexus, the renal plexus. The nerves are composed 

 partly of medullated fibres of very different sizes but chiefly of 

 non-medullated fibres ; numerous small ganglia, differing however 

 very much in size, are scattered over the plexus. 



The, nerves thus forming the renal plexus come chiefly from the 

 great solar plexus, and appear to be more immediately connected 

 with the part of that plexus which is called the semilunar ganglion. 

 The plexus is therefore indirectly connected with the nerves 

 entering into the solar plexus, such as the right vagus and the 

 splanchnic nerves, great and small. Besides this one or two nerve 

 strands, leaving the sympathetic chain below the splanchnics 

 appear to pass directly to the renal plexus ; filaments have also 

 been traced to the left kidney from the left vagus (which does not 

 join the solar plexus), and it is contended that filaments from the 

 right vagus also, make their way direct to the right kidney, with- 

 out distinctly communicating with the solar plexus. Some of the 

 fibres destined for the kidney which run in the splanchnic nerves 

 appear to be connected with nerve-cells in the solar plexus and, 

 losing their medulla there, to run on to the renal plexus as non- 



